1. Field of the Invention
The present invention relates to a digital broadcast receiving terminal, and more particularly to such a terminal configured to rapidly recover audio/video lip synchronization (Lipsync) of recorded stream data.
2. Discussion of the Related Art
FIG. 1 is a diagram depicting a terminal operatively associated with vehicle 5, which is in motion relative to broadcasting center 10. While the vehicle is in motion, the terminal may receive a digital broadcast transmitted from broadcasting center 10 along various paths. By way of example only, the terminal is shown receiving a digital broadcast along paths A, B, and C via satellite 20, and along paths A-1, B-1, and C-1 through repeater 30. The repeater acts as a gap filler to provide broadcast coverage in the satellite shadow regions.
Transmission paths A, A-1, C, and C-1 are examples of acceptable reception environments during which the terminal may receive broadcast signals of sufficient strength and quality. Conversely, transmission paths B and B-1 represent a compromised reception environment during which the terminal does not receive the desired signal level.
FIG. 2 provides an example of stored digital stream data which may result from receiving a digital broadcast by the moving terminal of FIG. 1. The illustrated arrangement includes three distinct sections of stored digital stream data, and more specifically, a discontinuous section between two continuous sections. Both continuous sections are defined by stream data having been received in a continuous manner.
In accordance with the example of FIG. 2, stream data 1 is consistent with data received during a period of time that the moving terminal was located along transmission path A or A-1 (FIG. 1). On the other hand, stream data 2 is consistent with data received during a period of time that the moving terminal was located along transmission path C or C-1. The third region represents a discontinuous region during which the moving terminal was located in a compromised reception environment (e.g., tunnel 35), such as when the moving terminal was located along transmission (or lack thereof) path B or B-1.
Stream status data is typically used to identify the continuous or discontinuous status of data received at the terminal. The example of FIG. 2 therefore results in stream status data having a “continuous” value when the moving terminal receives either of stream data 1 or stream data 2. Stream status data may have a value of “discontinuous” when the terminal is located in a compromised receiving environment, such as along transmission path B or B-1.
Stream data that has been stored with a discontinuous section presents a problem during playback of the stream data. In particular, a time information error may occur because of the lack of continuity of recording the stream data. This lack of continuity requires a significant amount of time to recover lipsync of the audio and video of the stream data.